There are a variety of methods available to detect the source of downhole leak points include Production logs, down-hole cameras, thermal decay logs, and noise logs. However, many of these methods are not so much effective specially in case of very small leaks and can result in gathering data that requires a significant amount of logging assurance to interpret. Continuous logging has proven to be significantly more efficient in locating anomalies than static logging techniques commonly used in noise logging operations. Identification of the source of pressure communication between well tubing-casing and casing-casing annuli presents a huge challenge to petroleum engineers.
This paper presents a brief description of two technologies for leak detection and the findings from the field trial. In this well two type of logging techniques are used: Production logging and Noise logging. These tools were run in an oil well with a history of leaking oil 600 meters away at surface. Analytical work prior to the trial had established that the wellhead seals and burning pit flow line were not the source of leak. The paper describes the interpretation of the results that indicated a possible casing leak. The results show that in Noise logging the source of leak is clearer than production logging. In some cases two logs have read the same values.